Math in the Old Days
The Mayans were using this by the 4th century; the concept of that number didn’t make it to Europe until the 1200s or so
Zero
An ancient Hindu text calculates the square root of this integer as 1.4142156 which is correct to 5 decimal places.
2
The Babylonians used base 60, which would be counted on 5 fingers of one hand & the 12 of these on 4 fingers of the other.
The knuckles
Some think Ancient Egyptians represented fractions using symbols from the eye of this falcon god.
Horus
Their numerals weren’t handy for arithmetic, so ancient Romans did most of their calculating on this device.
An abacus